2,6-Di(tert-butyl)-4-[3-[2,6-di(tert-butyl)-4H-thiopyran-4-ylidene]-1-propenyl]seleninium C??? ??, ??, ??

2,6-Di(tert-butyl)-4-[3-[2,6-di(tert-butyl)-4H-thiopyran-4-ylidene]-1-propenyl]seleninium ?? ?? ? ???

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2,6-Di(tert-butyl)-4-[3-[2,6-di(tert-butyl)-4H-thiopyran-4-ylidene]-1-propenyl]seleninium ?? ??